Material handling apparatus having seperate workstation and method of use

ABSTRACT

A workstation for a material handling system is provided. The system may include a plurality of vehicles for retrieving items from a plurality of storage locations located in one or more racks. The workstation is configured to accommodate the vehicles so that the vehicles drive into the workstation and drive upwardly along a track in the workstation. In one configuration, the track is configured to tilt the vehicle at a predetermined angle relative to the horizon as the vehicle is driven upwardly. After the vehicle is tilted to the predetermined angle the vehicle continues to drive upwardly while maintaining the predetermined angle.

PRIORITY CLAIM

This application claims priority to U.S. Provisional Patent ApplicationNo. 63/065,524 filed on Aug. 14, 2020. The entire disclosure of theforegoing application is hereby incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a material handling system for storingor retrieving items. More specifically, the present invention relates toa material handling system incorporating a plurality of destinationareas and a plurality of vehicles for carrying items to and/or from thedestination areas and to and/or from one or more workstations.

BACKGROUND OF THE INVENTION

Storing and retrieving items to fill a customer order can be laboriousand time consuming, especially in a system that stores thousands ofitems. Storing and retrieving items from thousands of storage areasrequires significant labor to perform manually. In many fields,automated picking has developed to reduce labor cost and improvecustomer service by reducing the time it takes to fill a customer order.However, the known systems of automatically handling the materials areeither very expensive or have limitations that hamper theireffectiveness. Accordingly, there is a need in a variety of materialhandling applications for automatically storing and/or retrieving items.

SUMMARY OF THE INVENTION

The present invention provides a number of inventive aspects that relateto material handling and/or storage and retrieval processes.

According to one aspect, a pick station for a material handling systemhaving a plurality of independently operable vehicles delivering itemsis provided. The pick station optionally includes a housing. The housingmay have an opening configured to facilitate the vehicle entering thepick station. Additionally, the pick station includes a track having afixed track positioned within the housing so that vehicles drivingthrough the opening in the housing drive into operative engagement withthe fixed track. The fixed track may be configured to guide vehiclesvertically upwardly. Additionally, the track may include a lower sectionhaving a curved profile to tilt the vehicle to a predetermined anglerelative to the horizon. The track may also include an upper sectionhaving a substantially straight profile to raise the vehicle at thetilted angle for a predetermined distance.

According to a further aspect, a pick station may include a monitor foridentifying the items to be removed from the container delivered to thepick station by a vehicle.

According to another aspect, a pick station may include a track thatincludes a plurality of vertical tracks.

According to a further aspect, a pick station may include a track thatincludes a plurality of teeth.

According to a yet another aspect, a pick station may include a trackhaving a first track element having a lower section having a first toothpitch and an upper section having a first tooth pitch. Optionally, thetrack may have a second track element opposing the first track elementand having the first tooth pitch along substantially the entire lengthof the second track element.

According to a further aspect, a method may be provided for charging amaterial handling vehicle configured to drive along a first pathway in ahorizontal direction and a second pathway in a vertical direction. Eachvehicle may include a power storage element. The method may include thestep of driving a vehicle having an item to a pick station having acharging element that includes a conductive element configured toprovide a charging current to the vehicle to charge the power storageelement of the vehicle. The method may also include the step ofdisplacing an electrical contact of the vehicle into engagement with thecharging element. Optionally, the vehicle may be raised at the pickstation while the electrical contact maintains electrical engagementwith the charging element. Additionally, the charging element may bedisplaced while the vehicle is raised upwardly at the pick station.

According to another aspect, a method is provided for charging amaterial handling vehicle that includes the step of driving the vehicleupwardly at a pick station.

According to a further aspect, a method is provided for charging amaterial handling vehicle having a step of driving the vehicle upwardlyby actuating a drive assembly of the vehicle.

According to yet another aspect, a method is provided for charging amaterial handling vehicle that includes the step of displacing thecharging element and the step of displacing includes the step ofvertically displacing the charging element to maintain the chargingelement in operative engagement with the charging contact of the vehicleas the vehicle is raised upwardly.

According to a further aspect, a method for charging a material handlingvehicle includes the step of biasing the charging element in a verticaldirection relative to the charging contact of the vehicle. Optionallythe method may additionally or alternatively include the step of biasingthe charging element in a horizontal direction relative to the chargingcontact of the vehicle.

According to another aspect, a method for charging a material handlingvehicle may include the step of driving a vehicle with a container tothe pick station. Optionally, the method may include the step of drivingthe vehicle upwardly to an upper position so that the container ispositioned at an elevated position to present the container to anoperator at the pick station.

The present invention also provides a method for delivering items from astorage system to a pick station. The method for delivering itemsincludes the step of driving a vehicle having a container to a pickstation. The vehicle drives upwardly at the pick station to an upperposition to displace the container to an elevated position to presentthe container to the operator. The container may be releasably retainedin the elevated position. Optionally, the vehicle may be drivendownwardly away from the upper position while the container is retainedin the elevated position. Driving the vehicle downwardly while thecontainer is retained in the elevated position may operate to separatethe vehicle from the container. The method may also include the step ofdriving one or more subsequent vehicles to the pick station to deliveritems to be placed in the container while the container is retained inthe elevated position.

According to another aspect, a method for delivering items from astorage system to a pick station may include the steps of driving aretrieval vehicle upwardly at the pick station to the upper positioninto operative engagement with the container while the container isretained in the elevated position. Additionally, the method may includethe step of releasing the container. Optionally, the method may includethe step of driving the retrieval vehicle downwardly with the releasedcontainer. Additionally, the method may include the optional step ofdriving the retrieval vehicle horizontally away from the pick stationafter the step of driving the vehicle downwardly.

According to another aspect, the present invention may provide aworkstation for presenting items carried by vehicles having a horizontaldrive system for driving the vehicles horizontally along the ground anda vertical drive system for driving the vehicle vertically. Theworkstation may include a track system that includes a rear track havinga plurality of drive teeth, a front track having a plurality of driveteeth, and a carriage. The carriage optionally includes a first transfermechanism cooperable with the rear track to drive the carriage upwardlyand a second transfer mechanism cooperable with the front track to drivethe carriage upwardly. The first and second transfer mechanisms may beconfigured to engage the vertical drive system of the vehicle so thatpower from the vertical drive system is transferred through the firstand second transfer mechanisms to drive the carriage up the track systemto present an item on the vehicle to an operator at the pick station.

According to another aspect, the present invention may provide aworkstation having first and second transfer mechanisms and one of thetransfer mechanisms optionally includes a first gear having a firsttooth pitch and a second gear element having a second tooth pitch.Optionally, the workstation may include a front track having a firstsegment having a tooth pitch corresponding with the first tooth pitchand a second segment having a tooth pitch corresponding to the secondtooth pitch. Optionally, the first segment includes a curved profileconfigured to tilt the vehicles to a predetermined angle and the secondsegment is generally straight.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary and the following detailed description of thepreferred embodiments of the present invention will be best understoodwhen read in conjunction with the appended drawings, in which:

FIG. 1 is a diagrammatic plan view of a material handling system;

FIG. 2 is a fragmentary side elevation view of a portion of the materialhandling system illustrated in FIG. 1 ;

FIG. 3 is a perspective view of a vehicle for use with the materialhandling system illustrated in FIG. 1 ;

FIG. 4 is an end view of the vehicle illustrated in FIG. 3 ;

FIG. 5 is a side elevational view of the vehicle illustrated in FIG. 3 ;

FIG. 6A is a perspective view of a workstation for use with the materialhandling system illustrated in FIG. 1 ;

FIG. 6B is a perspective view of an alternate workstation for use withthe material handling system illustrated in FIG. 1 ;

FIG. 7 is an enlarged fragmentary rear perspective view of theworkstation illustrated in FIG. 6A;

FIG. 8 is an enlarged fragmentary front perspective view of theworkstation illustrated in FIG. 6A;

FIG. 9 is a perspective view partially broken away of the workstationillustrated in FIG. 6A, illustrating a track of the workstation;

FIG. 10 is an elevational end view of the track illustrated in FIG. 9 ;

FIG. 11 is a rear perspective view of the track illustrated in FIG. 9 ;

FIG. 12 is an enlarged elevational end view of the workstationillustrated in FIG. 9 , illustrating a carriage of the workstation;

FIG. 13 is an enlarged fragmentary front perspective view partiallybroken away of the carriage illustrated in FIG. 12 ;

FIG. 14 is an enlarged fragmentary rear perspective view partiallybroken away of the carriage illustrated in FIG. 13 ;

FIG. 15 is an enlarged perspective view of a gear of the carriageillustrated in FIG. 12 ;

FIG. 16 is an enlarged fragmentary perspective view partially brokenaway of a guide for the carriage illustrated in FIG. 12 ;

FIG. 17 is an enlarged fragmentary perspective view of the workstationillustrated in FIG. 6 a illustrating details of a safety door;

FIG. 18 is an enlarged fragmentary view of a vertical drive gear of thevehicle illustrated in FIGS. 3-5 ; and

FIG. 19 is diagrammatic overhead view of the workstation of FIG. 6B.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures in general and to FIG. 1 specifically, anapparatus for sorting or retrieving items is designated generally 10.The apparatus 10 includes one or more mechanisms for retrieving itemsfrom one of a plurality of locations, such as storage areas 25 locatedin racks 20. The retrieval mechanism may include one or more vehiclesthat retrieve items from the storage locations and deliver the items toa workstation 200 where an operator can retrieve the item from thevehicle. The vehicle then returns to a storage area in the rack to storeany remaining items that were not retrieved by the operator. The vehiclecan then advance to another storage area to obtain the next item to beretrieved. In this way, the system may include a mechanism forcontinuously storing and retrieving items to/from the various storageareas so that the items can be presented to an operator.

It should be understood that various items and subassemblies of theoverall system can be used alone or in combination with materialhandling systems having different structure or operation to the systemillustrated in the Figures and described below.

The material handling system 10 may include any of a variety ofdifferent systems for storing items. For instance, the material handlingsystem may include a system that incorporates a plurality of autonomousvehicles such as the system described in U.S. patent application Ser.No. 16/992,703, publication as no. 2021/0047117 on Feb. 18, 2021. Theentire description of U.S. appl. Ser. No. 16/992,703 is herebyincorporated herein by reference.

As illustrated in FIG. 1 , the material system may optionallyincorporate one or more racks 20. Each rack may include a plurality ofstorage locations 25. Optionally, the storage locations may be arrangedinto one or more vertical columns 22. For instance, FIG. 1 illustrates aplurality of racks 20 and each rack may include a plurality of columns22, each of which includes a plurality of storage locations. The itemsthat are handled by the system may be stored directly in the storagelocations. Alternatively, the items may be stored in bins or totes 55and the storage locations 25 may be configured to store the totes 55 asshown in FIG. 2 . Accordingly, it should be understood that unlessstated otherwise in the following description, when a tote is mentioned,the term tote is broad enough to include a container for containing oneor more items as well as simply being an item that is not necessarilycontained in a container.

Referring again to FIG. 1 , the system may include a plurality of racks20 that optionally may be positioned to form rows or aisles 50. Forinstance, a first rack 20 a may be spaced apart from a second rack 20 bso that an aisle 50 a is formed between the two racks. In particular,the first rack 20 a may be substantially parallel to the second rack toform an aisle having a substantially uniform width. Additionally, thesystem may include a plurality of racks forming a plurality of aisles50. Although the aisles 50 are illustrated in FIG. 1 as being parallel,it should be understood that if the system incorporates a plurality ofracks 20, the racks may be arranged in a variety of configurations andif the system includes a plurality of aisles 50, the aisles need not beparallel.

Optionally, the system includes an automated element for storing andretrieving totes from the storage locations. One such automated elementis an autonomous vehicle. For example, as discussed further below, theautomated element may include a plurality of autonomous vehicles 100.Additionally, the automated vehicles 100 may be configured to transportthe totes 55 to workstations 200. At the workstation 200, one or moreitems may be removed from a tote on one of the vehicles 100. In oneembodiment, a human operator may remove an item from the vehicle.However, it should be understood that an automated mechanism may removethe item from the vehicle. Accordingly, it should be understood that theoperator that handles items at the workstation(s) 200 may be a humanoperator or an automated mechanism or a combination of the two.

The system 10 and/or various components of the system may be controlledby a central controller 90, such as a microcomputer. The centralcomputer may receive signals from various elements, such as sensors andcontrol various aspects of the system based on signals received from thevarious components. The central controller may also store data regardingthe location of various items to be retrieved from the system.Additionally, the central controller may include data regarding theidentification of items to be retrieved, such as a number of items tofill customer orders, as well as the quantity of such items. In thisway, the central controller may control and coordinate the operation ofvarious elements to schedule the retrieval and processing of a varietyof items from the storage locations.

Rack System

As noted above, the system may include one or more racks 20 having aplurality of storage locations 25. The details of an exemplary storagerack 20 is illustrated in FIGS. 1 and 2 . However, it should be notedthat the system may include any of a variety of elements for organizinga plurality of storage locations 25.

Referring to FIG. 2 , each rack may include a plurality of support legsthat extend substantially vertically and a plurality of brackets thatextend substantially horizontal interconnecting the support legs. Thebrackets may be planar elements forming shelves so that the shelves formstorage locations. However, in the embodiment illustrated in FIG. 2 ,the horizontal brackets are L-shaped brackets that form horizontalledges to support edges of the totes 55. The horizontal brackets may bespaced apart from one another up the height of the vertical legs to forma column 22 of vertically spaced apart storage locations 25.

As discussed above, the system may include a plurality of racks that arespaced apart to form one or more aisle 50. Optionally, a track 40 may bepositioned along one or more of the racks and the track may beconfigured to guide vehicles vertically so that the vehicles may beconveyed up and down the column 22 to the storage locations in thecolumn. Additionally, it may be desirable to position a first trackalong a rack on one side of the aisle, such as along rack 20 a and asecond track along a rack on the opposite side of the aisle, such asalong rack 20 b. The vehicles 100 may be configured so that the vehicletravels in the aisle 50 a traveling vertically along a track on rack 20a while simultaneously travelling vertically along a track on rack 20 b.

If the system utilizes one or more vehicles and one or more racks, theracks may be configured to allow the vehicles to travel under the racks20 as well as being able to travel across or along any aisles that maybe incorporated into the system. For instance, referring to FIG. 1 , thevehicles may follow a path that moves along one or more path segmentsthat may be parallel or transverse to the aisle. A first such path isdesignated as path 60 a. Path 60 a is within and parallel to aisle 50 a.A second such path is designated path 60 b, which is parallel to thelength of aisle 50 a, but spaced apart from the aisle. Specifically,path 60 b is located under rack 20 b. Rack 20 b may be configured toprovide clearance for movement of the vehicle under the lowermoststorage location 25 so that the vehicle may travel under the rack 20 balong a path 60 b that is parallel to the length of the aisle. A thirdpath is designated 60 c, which is transverse 60 a and 60 b. As shown inFIGS. 1 and 2 , path 60 c is parallel to the depth of each column 22.

FIG. 2 illustrates a plurality of vehicles in different orientationsrelative to the racks 20 and the storage locations 25. For instance, afirst vehicle 100 a is oriented for horizontal movement along path 60 c,transverse the length of aisle 50. A second vehicle 100 b is orientedfor horizontal movement under the rack along path 60 b that is parallelto the length of the aisle 50. Additionally, a third vehicle 100 d ispositioned within the aisle 50 to climb vertical tracks along the racks20 on either side of the aisle. A fourth vehicle 100 e is alsopositioned within the aisle and has climbed up the track 40 a,b to astorage location 25 in an upper portion of the column 22. Finally, afifth vehicle 100 f is positioned under the rack 20 and is oriented atan intermediate position between the orientation of vehicle 100 a andthe orientation of vehicle 100 b. In particular, the racks may beconfigured to facilitate the vehicles turning horizontally underneaththe racks. The fifth vehicle 100 f illustrates the vehicle in theprocess of turning under the rack from a first path to a second path.

Vehicles

FIG. 3 illustrates details of one of the vehicles 100 that are shown inFIG. 2 . As noted above, if the system incorporates vehicles, thestructure of the vehicle may vary. Accordingly, it should be understoodthat each of the vehicle's features discussed below are optionalfeatures that may be varied or eliminated depending on the application.

The vehicles 100 may be autonomous systems that include an onboard powersupply for driving the vehicle. The vehicles may also include acommunication system for wirelessly receiving and transmitting controlsignals between each vehicle and a control element, such as the centralcontroller 90. In this way, the vehicle may receive control signalsregarding the location for retrieving an item and the location to whichthe vehicle is to deliver the item.

The vehicle illustrated in FIG. 3 includes a horizontal drive assembly120 for driving the vehicle 100 in a horizontal direction. Thehorizontal drive 120 may be configured to drive the vehicle along atrack or along an open horizontal surface, such as a floor. Forinstance, one option for a horizontal drive includes a plurality ofrotatable elements, such as wheels or rollers. One or more drivemechanisms may be provided for turning the rotatable elements.Additionally, the rotatable elements may turn from side to side to steerthe vehicle.

Alternatively, as illustrated in FIGS. 3-5 , the vehicle may have ahorizontal drive 120 formed of a plurality of rollers 122, 123, 124 thatare rotatable around a first axis, such as around an axle. Additionally,the rollers 122, 123, 124 may be constrained to rotation about a singleaxis. For example, in the embodiment illustrated in FIGS. 3-5 , thehorizontal drive 120 includes a pair of central rollers 124 and firstand second sets of outer rollers 122, 123. The first set 122 ispositioned forwardly of the central rollers while the second set ofrollers 123 is positioned rearwardly of the central rollers 124. Theouter rollers 122, 123 may include rollers spaced apart along the lengthof a horizontal axle so that each set of outer rollers includes a firstroller 122 a on one side of the vehicle and a second roller 122 b on anopposite side of the vehicle as shown in FIG. 4 . Additionally, as shownin FIG. 4 , each set of outer rollers may include a pair of rollers 122b on each side of the vehicle.

As noted above, the vehicle 100 may have any of a variety of steeringmechanisms for controlling the direction of travel of the vehicle. Forexample, an optional steering mechanism is a zero-turn mechanism thatcan turn the vehicle without substantially moving forwardly. Optionally,the zero-turn mechanism provides a means for turning the vehicle about avertical axis extending through the vehicle.

The zero-turn mechanism comprises a linkage that allows the wheels orrollers on one side of the vehicle to rotate at a different speed thanthe wheels or rollers on the opposing side of the vehicle. Optionally,the linkage allows the wheels or rollers on one side of the vehicle torotate in different directions than the wheels or rollers on theopposing side of the vehicle. In this way, by varying the speed and/orrotational direction of the wheels on one side of the vehicle relativeto the speed and/or rotational direction of the wheels on the opposingside of the vehicle, the zero-turn mechanism changes the direction oftravel to steer the vehicle.

Optionally, the system may also include one or more guides 80 to guideor align the vehicles as they travel. For instance, referring to FIG. 4, the guide 80 may include a channel or groove and the vehicle mayinclude a corresponding guide element that cooperates with the guide 80to control movement of the vehicle 100. One example of a guide elementis a follower 126. The follower may be any element configured to engagewith or cooperate with the guide 80. In the present instance, thevehicle 100 includes a central follower 126 that includes a rotatableelement such as a bearing that rotates about a vertical axis. Thecentral follower 126 engages the channel in the guide 80 to constrainhorizontal movement of the vehicle.

Optionally, the vehicle may also include one or more lateral guidemember 127. The lateral guide members 127 may cooperate with an outersurface of the guide 80 to constrain movement of the vehicle. Forinstance, guides 80 may comprise circular guides having acircumferential surface for guiding the rotation of the vehicles. Thevehicle may have a pair of lateral guide members 127 spaced apart fromone another a distance equal to the diameter of the circumferentialsurface of the guide. In this way, the lateral guides 127 engage thecircumferential surface of the guide to constrain the vehicle torotational motion.

In addition to the horizontal drive mechanism 120 the vehicle may alsoinclude a vertical drive mechanism 140 for driving the vehicle 100vertically within the rack 20. In particular, as noted above, the systemmay include a guide mechanism such as a track 40 that is disposedadjacent the rack 20. The vertical drive mechanism 140 may be configuredto cooperate with the vertical guide mechanism 40 to drive the vehicle100 vertically.

FIGS. 3-4 illustrate an exemplary vertical drive 140 that includes aplurality of rotatable gears 145, however, it should be understood thatthe vertical drive 140 may include any of a number of drive mechanismsfor driving the vehicle vertically. Referring to FIG. 4 , the verticaldrive may include drive gear 145 that rotates about a horizontal axisthat is transverse the horizontal axis of rotation of the horizontaldrive mechanism 120. In particular, optionally, the vehicle includes apair of drive gears 145 that are spaced apart from one another so thatteeth of a first one of the gears 145 b project outwardly from a firstside of the vehicle and teeth of a second one of the gears 145 d projectoutwardly from a second side of the vehicle as shown in FIG. 4 . Thesefirst and second gears 145 b,d may be synchronously driven.Additionally, as shown in FIG. 3 , the vehicle may include two pairs ofvertical drive elements that are spaced apart from one another along thelength of the vehicle. In particular, optionally, the vehicle includes afirst pair of vertical drive elements 145 a,c at a first end of thevehicle and a second pair of vertical drive elements 145 b,d at a secondend of the vehicle.

Referring to FIGS. 2 and 3 , the rack 20 may be configured so that thetrack 40 a on one rack is spaced apart from the track 40 b on a secondrack a distance corresponding to the spacing between the first set ofvertical drive elements 145 a and the second set of drive elements 145b. In this way, the first vertical drive element 145 a may cooperatewith the first track 40 a to drive the vehicle up the first track 40 a,while the second vertical drive element 145 b may cooperate with thesecond track 40 b to drive the vehicle up the second track 40 b.Optionally, the two vertical drive elements 145 a,b are synchronouslydriven so that the vehicle maintains a horizontal orientation as thevehicle moves from horizontal movement to vertical movement.

The vertical drive 140 may optionally be configured so that verticaldrive has a width that remains substantially constant as the vehicletransitions from horizontal movement to vertical movement. In this way,the vertical drive 140 need not telescope of extend outwardly totransition from horizontal driving to vertical driving. For example,referring to FIGS. 3-4 forward climbing gears 145 b and 145 d each havea horizontal axis of rotation and the spacing between the horizontalaxis of rotation of drive member 145 b is fixed relative to thehorizontal axis of rotation of drive member 145 d while the vehicle ismoving horizontally and while the vehicle is climbing.

The vehicle may also include an optional transfer mechanism fortransferring items between the vehicle and a destination, such as astorage location.

The transfer mechanism 150 may be operative to transfer an item betweena platform surface of the vehicle and one of the plurality ofdestination areas 25. As shown in FIG. 3 , the platform surface isoptionally defined by the exterior surfaces of a plurality of rollers.

The transfer mechanism 150 may be any of a variety of mechanisms forloading items onto the vehicle and for unloading items from the vehicleinto one of the storage areas. Additionally, the transfer mechanism 150may be specifically tailored for a particular application. In thepresent instance, the transfer mechanism 150 comprises one or moredisplaceable element(s) configured to engage an item stored at a storagelocation and pull the item onto the vehicle. More specifically, in thepresent instance, the vehicle includes one or more displaceableelement(s) configured to move toward a tote in a storage location andreleasably engage the tote. After the displaceable element(s) engage thetote, each displaceable element is displaced away from the storagelocation, thereby pulling the tote onto the vehicle 100.

The displaceable element of the transfer mechanism may any of a varietyof items, such as a bar, rod, or another element configured to engage anitem, for example, a tote. For example, referring to FIGS. 3-4 , thetransfer mechanism 150 may include one or more displaceable pins 152.Additionally, the transfer mechanism may include a drive element fordisplacing the pins 152. For instance, optionally, the transfermechanism 150 includes two drive elements in the form of endlesscarriers such as a drive belt or drive chains 154. Optionally, each pin152 projects or extends inwardly toward the longitudinal center line ofthe vehicle. The transfer mechanism is preferable configured tocooperate one of the totes to releasably engage the tote. For example,in the present instance, the pins 152 are configured to mate with arecess on the tote so that the transfer mechanism can engage the tote.However, it should be recognized that the transfer mechanism may includeany of a variety of elements for engaging items to be transferred ontoof off of the vehicle.

The vehicle includes one or more drive elements for driving the transfermechanism. Optionally, the vehicle includes one or more motors thatdrive the transfer mechanism 150. For instance, one or more motors ofthe vehicle drive system may drive the chains 154 to selectively movethe chains and pins 152 toward or away from storage locations.

As the vehicle approaches a storage location to retrieve a tote, thechains may drive the displaceable pins 152 toward the storage locationso that the pins underlie a groove or notch in the bottom of the tote.The vehicle travels a small distance upward until the pins 152 aredisposed within the groove or notch of the tote. The chain 154 thenreverses so that the pins 152 move away from the storage location. Sincethe pins engage the tote within the notch, when the pins move away fromthe storage location, the pins pull the tote onto a surface of thevehicle. In this way, the transfer mechanism 150 is operable to retrieveitems from a storage location. Similarly, to store an item in a storagelocation 25, the chains 154 of the transfer mechanism 150 drive the pins152 toward the storage location until the item is in the storagelocation. The vehicle then moves downwardly to disengage the pins fromthe tote, thereby releasing the tote.

In this instance, as seen in FIG. 2 , two or more totes, such as totes55, may be coupled and decoupled from one another using matingconnectors. Optionally, totes 55 may be coupled and decoupled from oneanother through a series of lifting and separating movements implementedby movement of the vehicle 100. Optionally, the transfer mechanism 150may be actuated to pull a forward facing (“lead”) tote onto a surface ofthe vehicle so as to be fully supported by vehicle 100. If the totes arereleasably connected, this pulling motion advances the trailing tote(i.e., the one that is immediately behind the lead tote) into the aislefacing location. Optionally, the vertical drive mechanism of vehicle 100is then operated to drive the vehicle 100 vertically to uncouple thelead tote from the trailing tote(s). Once decoupling is completed, thedrive system may be actuated again to center the tote upon the vehicle100.

The vehicle 100 may include a separate drive element for driving thetransfer mechanism 150. Alternatively, the transfer mechanism may beinterconnected with one of the horizontal or drive elements of thevehicle. Specifically, the transfer mechanism may be connected with oneof the drive systems so that the drive system is selectively operablebetween driving the vehicle and driving the transfer mechanism.

For instance, the transfer mechanism may optionally be connected withone of the horizontal drive systems with a selectable connection so thatin a first orientation the drive system drives the vehicle horizontallyand in the second orientation the drive system drives the transfermechanism. An optional clutch mechanism may be selectively engaged anddisengaged to initiate and terminate transmission of power,respectively, from the motor(s) of the horizontal drive system to thetransfer mechanism, whereby the second drive system may be operatedindependently of the transfer mechanism. In this instance, the clutchmechanism may be configured as two clutch sub-assemblies which aresymmetrically arranged relative to a longitudinal centerline of vehicle100.

Workstation

Referring now to FIGS. 6A-17 , details of a workstation 200 that may beused in conjunction with or as part of an automated warehouse system 10are illustrated. It should be understood that the workstation 200 is notlimited to use in a particular automated warehouse system 10, so thatfeatures of the workstation 200 are independent of features of theautomated warehouse system 10, such as the racks 20 and the elementsutilized to retrieve items from the racks, such as the vehicles 100.

The workstation 200 may have a single work area, referred to as a pickstation 205 as shown in FIG. 6B. Optionally, the workstation may havetwo work areas 205 located side by side as shown in FIG. 6A. In thefollowing discussion, a single pick station 205 is described. It shouldbe understood that if the workstation includes two pick stations theneach of the pick stations are configured substantially similarly.

The pick station 205 may optionally be configured to work together withindependent vehicles such as the vehicles 100 described above.Accordingly, the pick station 205 may be configured to cooperate withthe vehicles to raise the vehicles upwardly so that an operator canreadily retrieve items from the vehicles while the operator ispositioned at the pick station. For instance, the pick station 205 mayincorporate an element for lifting each vehicle as the vehicle arrivesat the pick station 205. The lift element may be driven by the pickstation 205. For example, each pick station may include an elevator forlifting the vehicle and the pick station may include a motor or othermechanism for driving the elevator. Alternatively, as described below,the drive element for lifting the vehicle 100 may be provided by thevehicle.

The pick station 205 may include an enclosure 210 that provides ahousing for the pick station. The enclosure may include side walls 212and an upper surface 215. The housing may optionally include front legs222 that support the front of pick station 205 and rear legs 224 thatsupport the rear of the pick station. The front and rear legs 222, 224may include adjustable feet that extend or retract to adjust the heightof each leg. The side walls 212 may have openings 214 configured toallow the vehicles to drive into the pick station 205 through the sidewalls.

Referring to FIGS. 6A, 6B and 19 , the upper surface 215 may have a pickopening 216 so that the operator can reach through the pick opening toretrieve an item that is carried on the vehicle 100. The pick opening216 may have a length and a width that correspond with the length andwidth of totes 55 that may be used to store items in the storage racks20. Optionally, each tote may have an upper rim defining an uppersurface of each tote.

The inner length and width of the interior of the tote adjacent the rimmay be substantially similar to the length and width of the pick opening216. If the tote has such an optional configuration, the tote 55 mayspan the entire length and width of the pick opening so that when thetote is positioned within the pick opening the tote impedes passingbetween the rim of the tote and the edge of the pick opening. Inparticular, the tote is sized and configured to cooperate with the pickopening to prevent the operator's hand from passing between the tote andthe pick opening. In other words, the tote may operate as a stopimpeding an operator from extending an appendage through the pickopening 216 into the interior of the pick station 205.

Optionally, the workstation may include a projector 220 for projectinglight and optionally images onto the workstation. The projector 220 maybe mounted above the upper surface 215 for projecting light downwardlyonto the upper surface and onto the area surrounded by the pick opening216. The projector may be controllable by a central controller toselectably project light and images onto variable locations on the uppersurface 216 and/or onto areas of the tote 55 when the tote is raisedinto an upper position as shown in FIG. 19 .

As shown in FIG. 19 , the upper surface 215 of the pick station 205 mayframe the pick opening 216, thereby framing the tote 55. The uppersurface 215 optionally provides a projection surface onto which theprojector may project images that provide information for the operator.For instance, the projector 220 may project one or more images onto theupper surface and also project light onto a portion of the tote. In FIG.19 , the projector 220 projects a first image 405 onto the upper surfaceadjacent the tote. In this instance, the first image 405 represents thenumber of items to be removed from the tote 55. Optionally, as shown inFIG. 19 , the projector may simultaneously project a second image 410onto the upper surface adjacent the tote. The second image 410 providesa graphic representation of the item to be picked from the tote.Optionally, the projector may simultaneously provide an illuminationbeam 400 to illuminate a portion of the tote in which the item to bepicked should be contained. For instance, the projector may illuminatethe cell 56 from which the items should be picked.

The central controller monitors the vehicles and the cells within thetotes carried by the vehicles. The central controller additionallymonitors the number of items to be picked from a tote at a workstation.Accordingly, the central controller controls the projector so that whenthe tote is raised to the upper position, the projector projects one ormore identifying indicia for the operator. Preferably, the centralcontroller controls the projector to selectively project at least twoindicia, at least one of which includes a graphical image projected ontoa surface adjacent to the tote. The indicia are selectively projected inresponse to the tracking of the items in the totes and the dataregarding the number of items required.

Doors

As discussed above, the pick station may optionally be configured tocooperate with the totes so that the totes block the pick opening 216when the tote is raised up to the pick opening. Additionally, the pickstation may include an optional removable cover that selectively coversthe pick opening 216. For example, the pick station 205 may include amoveable closure mechanism or covering that overlies the pick opening toimpede items from passing through the pick opening. In a first position,the closure covers the pick opening to operate as a barrier preventingitems from passing through the pick opening; in a second position, theclosure uncovers the pick opening to allow items to pass through thepick opening. In one embodiment, the closure may be a moveable door 230.In a first position, the door is closed to cover the pick opening. In asecond position, the door moves away from the pick opening to uncoverthe pick opening as show in FIG. 6A.

The optional door 230 may be any of a variety of elements for coveringthe pick opening. One example is shown in FIGS. 6A, 8 and 17 , whichincludes a plurality of door segments 232 connected by a series ofpivotable connectors, such as hinges 234. The pick station may include amechanism for automatically driving the doors 230 between the openposition and the closed position.

As shown in FIG. 17 , a door closer 240 in the form of a belt 244 drivenby a drive shaft 246 may drive the door between the open position andthe closed position. The hinges 234 of the door segment may be attachedto a plurality of hinge blocks 242 that slide within a groove. Aconnector 242, such as a bracket or block, may interconnect one or moreof the hinge blocks 234 with the drive belt 244 so that driving thehinge blocks in a first direction extends the door over the pick opening216 and driving the hinge blocks in a second direction retracts the doorfrom the pick opening.

Track

The pick station 205 may include a mechanism for raising the vehicle 100at the pick station to present the tote 55 to an operator working at thepick station. For instance, the pick station may include an elevatorthat lifts the vehicle 100 after the vehicle enters the workstation 200.Such an elevator may be powered by a power source at the workstation.Alternatively, the vehicle 100 may provide the power source for liftingor raising the vehicle at the workstation 200. For example, theworkstation 200 may include a track or guide element 250 and the vehicle100 may include a climbing element for climbing the track. For instance,the vertical drive 140 of the vehicle 100 may cooperate with the track250 so that the vehicle may move vertically upwardly and downwardlywithin the workstation 200.

In the present instance, the workstation 200 may be configured so thattotes are tilted toward the operator when the tote is lifted toward theoperator. For example, the workstation 200 may include an optionalcurved track 250 that curves toward the front of the workstation so thatthe tote 55 tilts toward the operator as the vehicle drives upwardly.Referring now to FIGS. 10 and 11 , details of the optional curved track250 will be described in greater detail. It should be understood thatthe features of the curved track are optional so that one or more of thefeatures can be incorporated into the track while other features may beeliminated depending on the application.

Although the pick station is shown and described as having a housingthat encloses a frame that includes the curved track 250, it should beunderstood that in some applications the curved track may provide thestructural support for the pick station. And optionally, the housing maybe modified or eliminated.

An exemplary embodiment of an optional track 250 is illustrated in FIGS.10-11 . The track 250 includes a pair of front tracks 260 spaced apartfrom one another and a pair of rear tracks 270 spaced apart from oneanother. The front and rear tracks 260, 270 form four corners of avertical column that curves upwardly from back to front. The front andrear tracks may be rigidly connected. For instance, a pair of side bars226 may connect the front tracks 260 to the rear tracks 270.

As shown in FIG. 10 , each side bar 228 may extend at an angle relativeto the horizon, angling upwardly from front to back to rigidly connectthe top of one of the front tracks 260 with the top of the rear track270 that is on the same side of the pick station. Additionally, a pairof cross bars 228 may extend across the width of the pick station toconnect the front tracks 260 and the rear tracks. Specifically, a firstcross bar 228 may extend between the two front tracks 260 to rigidlyconnect the front tracks and a second cross bar 228 may extend betweenthe two rear tracks 270 to rigidly connect the rear tracks. In this way,the front tracks and the rear tracks may be connected to form afree-standing track.

If the track is curved as optionally shown in FIGS. 9-12 the length ofthe front track 220 is shorter than the length of the rear track 270.Therefore, the rearward end of the vehicle 100 that engages the reartrack 270 moves faster than the forward end of the vehicle that engagesthe front track 260. To accommodate this difference in speed, theinterface between the vehicle 100 and the track may be modified toaccount for the difference in relative velocity. For example, the frontand rear tracks 260, 270 may each have a plurality of teeth that operatesimilar to the teeth on a gear rack. The pitch of the teeth of the fronttrack may differ from the pitch of the teeth on the rear track. Forinstance, the front track may have a smaller tooth pitch, such as modulesized M4 than the rear track, such as M6. In this way, if the verticaldrive has vertical drive wheels that drive synchronously, the rearwheels travel a greater distance for each revolution of the verticaldrive wheels than the front wheel.

Although the track 250 may optionally include a front track that has adifferent pitch than the rear track, it should be understood thatalternative configurations may be incorporated to tilt the vehicle as itis raised at the pick station. For example, the vertical drive of thevehicle may be configured so that the vertical drive mechanism adjacentthe rearward edge of the pick station is driven faster than the verticaldrive mechanism adjacent the front of the pick station. In eitherconfiguration, the edge of the vehicle adjacent the rear edge of thepick station moves upwardly faster relative to the edge of the vehicleadjacent the front edge of the pick station.

As discussed above, the track and the vehicles may be configured tocooperate so that the rearward edge of the vehicle 100 adjacent the reartrack 270 moves upwardly relative to the forward edge of the vehicle sothat the vehicle is tilted toward the operator. In this way, totes arepresented to the operator for improved access to items in the tote.

Referring to FIG. 10 , the track 250 may optionally be configured sothat the track has a first section that tilts the vehicle as the vehicleis moved upwardly and a second section that drives the vehicle upwardlyat a constant angle relative to the horizon. In this way, the vehicletilts as it moves upwardly to a predefined point at which the vehicleforms a predefined angle relative to the horizon. After this predefinedpoint, the vehicle moves upwardly while maintaining the vehicle at thepredefined angle relative to the horizon.

FIG. 10 illustrates a track 250 having a lower section configured totilt the vehicle and an upper section configured to raise the vehicle ata constant angle relative to the horizon. For instance, the front track260 may have a lower curved section 262 that follows a radius ofcurvature. Similarly, the rear track 272 may have a lower curved section272 that follows a radius of curvature. The radius of curvature of therear lower track 272 is larger than the radius of curvature of the frontlower track 262. Additionally, the front track 260 includes an uppersection 266 that extends substantially linearly from the end of thelower curved section 262. Similarly, the rear track 270 includes anupper section 274 that extends substantially linearly from the end ofthe lower curved section 272. Additionally, the upper section 266 of thefront track may extend substantially parallel with the upper section 274of the rear track.

As described above, the front and rear tracks 260, 270 may have lowersections that curve and upper sections that are linear. Additionally,the tooth pitch of the two curved lower sections 262, 273 are differentto allow relative displacement of the front of the vehicle relative tothe rear of the vehicle. However, the tooth pitch of the linear uppersections 266, 274 may be constant so that the front and rear of thevehicle move at a substantially constant rate so that the angle of thevehicle relative to the horizon is substantially constant.

Since the tooth pitch of the lower sections is different but the toothpitch of the upper sections is the same, one of the tracks has differenttooth pitch on the curved section than on the linear section. In thepresent example, the front track has a curved lower section that has afirst tooth pitch, such as M4, and a linear upper section 268 havingsecond tooth pitch, such as M6. Optionally, the upper and lower sectionsare offset. Specifically, a lower groove 264 having a width may extendvertically alongside the lower curved section 262 so that the lowergroove 264 is substantially co-extensive with the lower curved section.The upper linear section 266 may have a width that is substantially thesame as the width of the lower groove and the upper linear section mayextend from the end of the lower groove 264. Additionally, an uppergroove 268 having a width that is similar to the width of the lowercurved track 262 may extend vertically alongside the upper linear track266.

Carriage

As described above, the workstation 200 may include a track 250 thatguides the vehicles so that the vehicles can climb vertically to presenttotes to the operator. The track 250 and the vehicles 100 may beconfigured so that the vehicles can directly engage the track to climbthe track. Alternatively, as described below, the workstation 200 mayinclude a carriage 300 that the vehicle rides on and which climbs thetrack to lift the vehicle toward the operator.

A variety of carriages can be used to lift the vehicle, including asingle-piece carriage that extends across the width of the side of theworkstation 200. Alternatively, as described below, the carriage maycomprise multiple independent sections. The elevator provides aninterface between a power source and the vehicle to raise the vehicle.For instance, the carriage may be connected with a power supply, such asa source of electricity that powers a motor to raise the vehicle.Alternatively, as described below, the carriage may provide a mechanismto utilize power from the vehicle to lift the vehicle. In the examplebelow, the carriage provides transfer gearing to transfer driving forcefrom the vehicle to a climbing mechanism that climbs the track 250 andtilts the vehicle.

The carriage 300 illustrated in FIGS. 7-10 and 12-16 includes a frontcarriage assembly 310 and a rear carriage assembly 320. The front andrear carriage assemblies 310, 320 are substantially similar, however oneof the two assemblies may include a charging assembly. As discussedbelow, the rear carriage assembly 320 is illustrated as incorporatingthe charging assembly. In the following description, the rear carriage320 will be described in detail. It should be understood that the frontcarriage 310 includes features similar to those described below for therear carriage except for the details regarding the charging assembly.

Referring now to FIGS. 7, 9 and 13 , the rear carriage 320 comprises anelongated substantially vertical side wall having a length that extendsbetween the two rear tracks 270. The side wall 322 may include a pair ofapertures 324 spaced apart along the length of the wall. The firstaperture may be adjacent the first rear track 270 and the secondaperture may be adjacent the second rear track.

Optionally, the rear carriage assembly 320 may include a plurality ofgears that cooperate with the vertical drive 140 of the vehicle to liftthe vehicle at the pick station 200. For instance, the rear carriage 320may include a first transfer gear 330 adjacent the first rear track 270and a second transfer gear 330 adjacent the second rear track. As shownin FIGS. 12-13 , the transfer gears 330 may extend through the windows324 in the side wall 322.

The transfer gears 330 may be rotatably mounted on a shaft 339. Theshaft 339 may be mounted on a yoke 338 that straddles the window 324 inthe side wall so that a first end of the yoke is on one side of thewindow and a second end of the yoke is on the opposite side of thewindow.

Referring to FIG. 12 , the transfer gears 330 operate as an idler gearbetween the vertical drive 140 of the vehicle and the track 250.Specifically, the transfer gear engages the drive gear 145 of thevertical drive 140 as well as the teeth of the rearward track section270. In this way, the vertical drive gear 145 drives transfer gear 330,which drives the carriage vertically along the track 270. Driving thevertical drive gear 145 in a first direction drives the carriageupwardly along the track 270; driving the vertical drive gear 145 in asecond direction drives the carriage downwardly along the track 270.

Optionally, the vehicle 200 may include structure for engaging thecarriage 300 so that the carriage supports the weight of the vehicle.For instance, the vehicle may include a support element projectinggenerally horizontally. In FIG. 12 , the support element is illustratedas a pin or post 165 and the vehicle may include a plurality of suchsupport elements. Optionally, the vehicle may include a support elementadjacent the four corners of the vehicle so that the front and back andboth sides of the vehicle are supported.

The carriage may include structure to cooperate with the verticalsupport elements 165 on the vehicle 200. For instance, as shown in FIG.13 , the carriage subassembly 320 may include one or more block, stop,bracket or other element 370 having a surface to support the verticalsupport elements 165 of the vehicle. The support bracket 370 may have ahorizontal surface to support the support pins 165. In the illustratedembodiment, the support bracket 370 includes a v-groove configured sothat the support pin 165 nests within the v-groove.

The support elements 165 on the vehicle may be positioned so that thesupport elements are spaced above the support brackets 370 on thecarriage 300 as shown in FIG. 12 . In this way, a clearance gap isformed between the top of the support bracket and the bottom of thesupport elements 165. The clearance gap allows the support pins 165 topass over the support brackets 370 when the vehicle drives into orthrough the pick station 200.

The support elements 165 on the vehicles cooperate with the supportbrackets 370 on the carriage to raise and lower the vehicle at the pickstation. For instance, the vertical drive gear 145 of the vehicle maydrive the transfer gear 330 of the carriage 300 to drive the carriageupwardly. As the carriage drives upwardly, the support brackets 370engage the support pins 165 so that the support pins rest within thev-groove in the support bracket. As the carriage drive further upwardly,the support brackets 370 support the weight of the vehicle via thesupport pins so that the carriage lifts the vehicle upwardly. Similarly,when the carriage is lowered the support brackets 370 support thesupport pins so that the vehicle is lowered with the carriage.

As described above, the front carriage assembly 310 may be substantiallysimilar to the rear carriage assembly 320. Additionally, as describedabove, the front track 260 may be configured differently than the reartrack 270, such as in an application where the track 250 curves to tiltthe tote 50 toward the operator at the pick station 200. Accordingly, itmay be desirable to configure the transfer gear 330 for the frontcarriage 310 different than the transfer gear for the rear carriage. Forexample, the transfer gear 330 for the rear carriage 320 may be an idlergear having a single set of gear teeth to cooperate with the rear track270 and the front carriage may incorporate a compound gear 330′ havingtwo sets of gear teeth as illustrated in FIG. 15 . However, it should beunderstood that if the front and rear carriages have different transfergears, the track may be configured so that the rear carriage has aplurality of gear elements, such as the compound gear shown in FIG. 15 .

Referring to FIG. 15 , the optional compound transfer gear incorporatedinto the front carriage 310 is illustrated. The transfer gear 330′ mayinclude two separate coaxial gears having different tooth pitches thatrotate at the same speed. However, in the present instance, the transfergear 330′ comprises a unitary piece with both gear elements fixedlyconnected with a central hub 332. For instance, the transfer gear mayhave a first gear 334 integrally formed with the central hub 332 that isconfigured to cooperate with a first portion of the front track 260 anda second gear 336 integrally formed with the central hub 332 that isconfigured to cooperate with a second portion of the front track. Forinstance, optionally, the first gear 334 is configured with a gear pitchdesigned to mesh with the upper portion 266 of the front track 260 andthe second gear 336 is configured with a gear pitch designed to meshwith the lower portion 262 of the front track. Additionally, thetransfer gear 330′ may be configured so that the first gear 334 has gearteeth having a greater tooth length than the gear teeth of the secondgear 336 so that the gear teeth of the second gear project outwardlyfrom the central hub 332 farther than the gear teeth of the first gear.

The transfer gear 330′ may be optionally mounted onto the front carriage310 so that the first gear 334 aligns with and/or overlies the lowergroove 264 of the front track. Additionally, the first gear may beconfigured so that the first gear does not mesh with or contact thelower rack section 262 of the front track 260. In this way, the firstgear 334 is spaced apart from the lower rack section so that the firstgear 334 does not engage the lower rack section.

Referring to FIGS. 11 and 15 , the transfer gear 330′ is configured andpositioned so that the smaller diameter gear 336 engages the lower racksection 262 to drive the vehicle 100 upwardly. At the same time, thelower groove 264 provides clearance for the larger diameter first gear334. As the vehicle climbs upwardly, the smaller gear 336 reaches theend of the lower track section 262. At the end of the lower tracksection, continued upward displacement of the vehicle causes thetransfer gear to transition from the lower track section 262 to theupper track section 266. The transition occurs as the larger gear 334engages the upper track section 264 and the upper groove 268 providesclearance for the smaller gear 336. When the first gear 334 engages theupper track section 266, continued driving of the transfer gear 330′drives the carriage upwardly along the upper track section.

Similarly, the upper and lower track sections cooperate with thetransfer gear 330′ to lower the carriage 300. Specifically, the firstgear 334 engages the upper track section 266 until the first gearreaches the end of the upper track. Continuing to drive the transfergear downwardly after the first gear reaches the end of the upper trackcauses the transfer gear to transition from the upper tracks to thelower track section so that the second gear 336 engages the lower tracksection while the lower groove 264 provides clearance for the first gear334.

As discussed previously, the vertical drive 140 of the vehicle 100 mayinclude a plurality of drive gears having teeth that project outwardly.Optionally, the spacing of the drive gears relative to one another maybe fixed during operation of the vehicle when the vehicle is travellingalong the ground and also when the vehicle is climbing in the racks.Similarly, the climbing gears may have a fixed spacing relationship whenthe vehicle is raised vertically at the workstation 200.

Accordingly, as shown in FIGS. 10 and 12 , when the vehicle is in theworkstation 200, the axis of rotation of the vertical drive gears 145 isparallel to the axis of rotation of the transfer gears 330 of thecarriage. Therefore, when incorporating this optional combination ofvertical drive elements and transfer gears, it is desirable to configurethe teeth of the vertical drive gears 145 and the transfer gear tofacilitate the teeth of the vertical gears passing through teeth of thetransfer gear as the vehicle enters the workstation.

As shown in FIG. 12 , the transfer gear 330 and the vertical drive gear145 may be aligned so that the vertical drive gears do not impinge uponor contact the transfer gear when the vertical gear is translatedrelative to the transfer gear. For instance, the spacing between theteeth of gear 334 provides sufficient clearance for the teeth of thevertical drive gear 145 to pass between the gaps between the teeth ofgear 334 when the vertical drive gear translates horizontally along aline that is parallel to the axis of rotation of the transfer gear 330.More specifically, the vertical drive gear and the transfer gear may beconfigured and positioned so that the addendum circle of the verticaldrive gear 145 overlaps with the addendum circle of the transfer gear330. While the addendum circles of the two gears overlap, the teeth ofthe gear are configured and oriented so that the vertical drive gearpasses through the gaps between teeth in the transfer gear 330.

Referring again to FIG. 12 , optionally, the vertical drive gear 145 andthe transfer gear 330 may be configured and oriented to increase theclearance for the vertical drive gear to pass through the transfer gearwhen the vehicle drives into the workstation (i.e. when the verticaldrive gear translates so that the axis of rotation of the vertical drivegear translates parallel to the axis of rotation of the transfer gear).Accordingly, the operating clearance of the vertical drive gear and thetransfer gear is maximized when the carriage is at its lowest point asshown in FIG. 12 .

As the carriage lifts the vehicle, the operating clearance between thevertical drive gear and the transfer gear may diminish so that the gearcenters move toward a standard center distance. Specifically, the track250 may be configured so that the distance between the front track andthe rear track is not constant along the height of the track. Forexample, the reference line of the teeth of the front and rear tracksmay be configured so that the distance between the two reference linesgradually reduces along the height of the track. The spacing between thereference lines of the tracks may continue to diminish along the entireheight of the track. However, in the present instance the spacing of thetrack reference lines reduces to a predetermined distance and thenremains constant for an upper portion of the tracks. By diminishing thedistance between the reference lines of the front and rear tracks, thetracks move the transfer gears toward the vertical drive gearsincreasing the contact ratio between the vertical drive gear and thetransfer gear.

As described above, when the vehicle enters the workstation, thevertical drive gear 145 and the transfer gear 330 are spaced apart at amaximum distance to maximize clearance to facilitate translation of thevertical drive gear relative to the transfer gear. Optionally, the track250 may be configured so that the track guides the transfer gear towardthe vertical drive gear as the carriage is driven up the track. In thisway, the system is configured so that the operating clearance is reducedas the vehicle is driven upwardly along the track.

The carriage 300 may be a unitary item that interconnects both the frontand rear carriage assemblies 310, 320. Alternatively, as shown in FIG.10 , the carriage may include separate front and rear carriages 310, 320that operate independently. If the carriage 300 includes separate frontand rear carriages it may be desirable to utilize a retainer to retainthe transfer gear 330 in operative engagement with the track 250.

Referring to FIGS. 11 and 16 , the details of an optional retainer areillustrated. The retainer may include an element mounted on theworkstation 200 that cooperates with an element mounted on each carriage310, 320 to retain the transfer gear 330 in operative engagement withthe track. In the present instance, a guide track 280 is mounted on thetrack 250. Specifically, the guide track 280 comprises an elongatedchannel or groove positioned adjacent each section of the track as shownin FIG. 11 . Additionally, a follower assembly 380 may be connected withthe carriage. It should be understood that the follower assembly may beconnected to each end of both the front and rear carriages 310, 320. Asshown in FIG. 16 , the follower assembly 380 includes a bracket 382connected with the rear carriage 320 and projecting transverse thesidewall 322 on the rear carriage. One or more inner following elements384 are mounted onto a distal end of the bracket remote from the sidewall of the rear carriage. The inner follower elements 384 areconfigured to cooperate with the groove of the guide track 280.

In the present instance, the inner follower elements 384 are rollerbearings having a diameter corresponding with the width of the groove inthe guide track 280. The follower assembly may also include an outerfollower element 386 configured to cooperate with a second surface ofthe guide track 280. For instance, the follower 380 may include a thirdbearing 386 spaced apart from the inner bearing 384. The gap between theinner and outer bearings 384, 386 may be similar to the wall thicknessof guide track 280 so that the inner bearing 384 follows the inner wallof the groove while the outer bearing 386 follows the outer wall of theguide.

Charging Assembly

The picking station 200 may optionally include a charging mechanism forcharging the vehicle 100. The charging mechanism may be connected withan electrical power source 95 to provide a charging current to re-chargethe power supply of the vehicles. For instance, optionally each vehicleincludes an onboard rechargeable power source. The rechargeable powersource may be a rechargeable battery. However, in the present instance,the vehicles comprise a power source that includes a plurality ofultracapacitors that can be rapidly re-charged. For example, the powersource may include a plurality of supercapacitors or ultracapacitorssufficient to power the vehicle as it moves horizontally or verticallywith a payload of 30-40 kilograms.

The charging mechanism may be any of a variety of elements for providinga charging current to the vehicle. For instance, in the presentinstance, the charging mechanism may be a charging rail 340 thatcooperates with electrical contacts 160 on the vehicle 100.

As shown in FIG. 13 , the charging rail 340 may comprise one or moreelongated electrically conductive elements. The rail may form one ormore channel or groove configured to cooperate with electrical contactsof the vehicle. For instance, as shown in FIG. 12 , the vehicle mayinclude one or more charging contacts, such as brushes 160. The brushes160 may project outwardly from the vehicle. The brushes 160 are orientedand configured to mate or cooperate with the charging rail 340. Forexample, as shown in FIG. 13 the charging rail may be horizontallyoriented and the charging rails may project horizontally outwardly fromthe rear side of the vehicle so that the brushes project into electricalcontact with the charging rail when the vehicle is in the carriage 300.

The charging rail 340 may be rigidly mounted to the track 250 or thehousing 210 so that the charging rail does not move relative to thetrack 250 or the housing 210. Alternatively, the charging rail may bedisplaceable relative to the track or the housing 210. Optionally, thecharging rail may be connected with the carriage so that the chargingrail moves with the carriage. For instance, the charging rail may movevertically upwardly and downwardly as the carriage 300 moves verticallyalong the track 250. In this way, the charging contacts 165 of thevehicle 100 may remain in electrical connection with the carriage 300 asthe carriage and the charging rail 340 are displaced vertically. Inother words, the charging rail 340 may be configured to continue toprovide a charging current to the vehicle 100 as the vehicle and thecharging rail are displaced vertically at the pick station.

Optionally, the charging rail 340 may be horizontally displaceablerelative to the vehicle 100 to horizontally align the charging contacts165 of the vehicle with the charging rail.

In one embodiment, the charging rail 340 may be displaceably connectedwith the carriage 300 so that the charging rail 340 is displaceablehorizontally toward and away from the vehicle. Optionally, the chargingcontacts of the vehicle may be displaceable horizontally and/orvertically relative to the charging rail 340.

A variety of connection may be incorporated to provide a displaceableconnection between the carriage 300 and the charging rail 340. Forinstance, the connection may be a biased connection so that the chargingrail is biased horizontally away from the sidewall 322 of the carriage300 toward the vehicle.

An optional embodiment that includes a biased connection is illustratedin FIG. 14 . In this embodiment, the carriage includes one or morelateral adjustment mechanisms 350 that bias the charging rail toward thevehicle 100.

The lateral adjustment mechanism 350 may include a plurality ofhorizontal rods 352 that are displaceable horizontally relative to amounting bracket 356. Additionally, the lateral adjustment mechanism 350may include one or more rigid rods that rigidly connect the bracket 356with the carriage. One or more biasing elements 354 bias thedisplaceable rods 352 toward the vehicle. The biasing elements 354 maybe any of a variety of elements, such as an elastomeric member or aspring. In the present instance, the biasing element is a coilcompression spring circumscribing the displaceable rods 352.

Optionally, the charging rail 340 may be vertically displaceablerelative to the vehicle 100 to vertically align the charging contacts165 of the vehicle with the charging rail. For instance, the chargingrail 340 may be displaceably connected with the carriage 300 so that thecharging rail 340 is displaceable vertically relative to the vehicle.

A variety of connection may be incorporated to provide a verticallydisplaceable connection between the carriage 300 and the charging rail340. In one embodiment, the connection may be a biased connection sothat the charging rail is biased vertically relative to the sidewall 322of the carriage 300.

An optional embodiment that includes a biased connection is illustratedin FIG. 14 . In this embodiment, the carriage includes one or morevertical adjustment mechanisms 360 that bias the charging railvertically relative to the vehicle 100. The vertical adjustmentmechanism 360 may include a vertical rod 362 that is displaceablevertically and a biasing element for biasing the charging rail in avertical direction. The vertical rod may be supported by one or moresupport elements. For instance, the vertical rod is supported betweentwo support blocks 364, such as pillow blocks or mounting blocks.

Optionally, the vertical adjustment mechanism 360 may include one ormore stops that limit the travel of the vertical rod relative to thesupport blocks 364. Although a variety of items can be used as such astop, FIG. 14 shows one non-limiting example in which the stops are snaprings positioned along the length of the vertical rod.

One or more biasing elements 363 bias the vertical rod 362 vertically.The biasing elements 363 may be any of a variety of elements, such as anelastomeric member or a spring. In the present instance, the biasingelement is a coil compression spring circumscribing the vertical rod362.

The optional displaceable connection of the charging rail 340 allows thecharging rail to displace relative to the vehicle as the vehicle entersthe carriage. In one example, the charging rail is displaceable in afirst direction to allow the charging rail to align with the electricalcontact(s) of the vehicle. Similarly, and optionally, the charging railis displaceable in a second direction transverse the first direction toallow the charging rail to align with the electrical contact(s) of thevehicle.

Additionally, the charging rail 340 may include one or more guides ordeflectors, such as tapered fingers 345 that are engageable with thebrushes 165 of the vehicle to align the brushes into the channels of thecharging rail. Specifically, the guides 345 may include one or moretapered surface to deflect the charging rail vertically relative to thebrush when the brush engages the guide.

In the foregoing example, the charging rail 340 may be vertically and/orhorizontally displaceably connected to the carriage 300 so that thecarriage is displaceable relative to the electrical contact(s) 165 ofthe vehicle. Alternatively, the charging rail 340 may be substantiallyrigidly connected relative to the carriage and the electrical contactsmay be vertically and/or horizontally displaceable relative to thevehicle to align the electrical contacts with the charging rail when thevehicle enters the carriage.

Tote Retainer

As described above, the vehicles 100 deliver items, such as totes 55 tothe workstation 200 and the vehicles are lifted vertically to raise thetote into a pick opening 216 so that an operator can remove an item fromthe tote. The vehicle then lowers back down toward the ground along withthe tote. However, there may be applications in which it is desirable toretain the tote in a raised position when the vehicle lowers down. Inthis way, the tote can remain in the raised position at the pick station205 while the vehicle 100 drives to a different location to perform aseparate task, such as to retrieve another tote 55. Accordingly, asshown in FIG. 17 , the pick station 205 may include an optional retainermechanism 290 for retaining the tote in the raised position.

The retainer mechanism 290 includes a mechanical element displaceablebetween a retracted position and an extended position. In the extendedposition, the retainer projects inwardly toward the tote. As shown inFIG. 9 , the totes may have an upper lip or flange. In the extendedposition, the retainer mechanism 290 projects toward the tote so thatthe retainer mechanism extends under the lip of the tote. In this way,the retainer operates as a stop impeding downward movement of the toteif the vehicle moves downwardly.

The retainer mechanism 290 can include any of a variety of elements forengaging the totes. FIG. 17 illustrates one exemplary mechanism.Specifically, the retainer mechanism may include a pivotable finger orarm 292, referred to as a paddle. The paddle 292 is a longitudinallyelongated element that pivots around a pivot axis located adjacent afirst end of the paddle. The second end of the paddle 292 pivots betweena retracted position and an extended position. In the retracted positionthe paddle is retracted away from the picking window 216 so that thetote can readily move up and down as the vehicle moves up and down onthe track 250. In the extended position, the paddle extends into thepick window 216 so that the paddle engages the tote to prevent the totefrom moving downwardly.

The retainer mechanism 290 includes a drive element for driving theretainer mechanism between the retracted position and the extendedposition. The drive element may be a separate drive mechanism, such as asolenoid, motor or other actuator. Optionally, as shown in FIG. 17 , thedrive mechanism for the door 230 covering the pick window 216 alsodrives the retainer mechanism. Specifically, a connector 294 connectedwith the door drive 240 is also connected with a linkage 296 connectedwith the paddle 292. In this way, actuating the door drive mechanismalso actuates the retainer mechanism 290. Additionally, it may bedesirable to bias the retainer mechanism into either the extended or theretracted position. In the present instance, a biasing element, such asa spring, biases the paddle toward the retracted position.

Optionally, the connection between the door drive 240 and the paddle 292is configured so that actuating the door drive from a closed position toan open position drives the paddle from retracted position to theextended position. Additionally, the door drive 240 and the paddle 292may be connected so that actuating the door drive from an open positionto a closed position drives the paddle from the extended position to theretracted position.

Operation

The system 10 and the various subassemblies described above may beconfigured to facilitate numerous methods of operations related tomaterial handling as described below.

The system 10 may include a plurality of autonomous vehicles 100 fordelivering items to workstations 200. The vehicles may be configured todrive along a horizontal pathway 60, such as driving along the ground.Optionally, the vehicles may drive along the ground to a storage areawhere a plurality of items are stored. For instance, a plurality ofitems may be stored in a plurality of containers, such as totes.Optionally, the totes may be stored in a plurality of racks 20 that arespaced apart forming longitudinally elongated aisles 50. The aisles maybe parallel with one another.

The vehicles 100 may drive under one of the racks 20 in a directionparallel to one of the aisles 50. The vehicle 100 may drive under therack until the vehicle reaches a destination column 22 in the rack,which is the column in which an item is to be stored or from which anitem is to be retrieved. Optionally, when the vehicle arrives at thedestination column the vehicle may rotate or turn to change thedirection of travel. For instance, while the vehicle is in thedestination column, the vehicle may change from a direction of travelparallel to the aisle to a direction of travel transverse the aisle.Alternatively, the vehicle may drive under the rack 20 to thedestination column along a path that is substantially perpendicular tothe aisle. After reaching the destination column, the vehicle optionallydrives perpendicular to the aisle into the aisle of the destinationcolumn.

In the aisle, the vehicle optionally drives upwardly to the destinationlocation 25 where the item is to be stored or from which the item is tobe retrieved. The vehicle may be raised up the column by an elevator orother mechanism. However, in the present instance, the vehicle includesa vertical drive mechanism 140 operable to drive the vehicle upwardly.Additionally, the system may include a track or guide 40 positionedadjacent the column and the vertical drive of the vehicle may engage thetrack or guide to drive the vehicle up the column to the destinationlocation.

Once the vehicle is raised to the destination location, an item, such asa tote 55, may be transferred between the vehicle and the destinationlocation. For instance, the vehicle may include a transfer mechanism fortransferring totes and the vehicle may actuate the transfer mechanism totransfer a tote from the vehicle to the destination location or totransfer a tote from the destination location to the vehicle.

After transferring an item between the vehicle and the destinationlocation, the vehicle optionally drives downwardly to a horizontal path,such as the ground. The vehicle may then drive horizontally along a paththat is perpendicular to the aisle.

The system may also include one or more workstations 200. The system mayinclude a method for operating an autonomous vehicle at a workstation200. For instance, the vehicle 100 may travel along a horizontal pathcarrying an item, such as a tote 55, to the workstation 200. The vehiclemay drive into the workstation to align the vehicle with apre-determined location within the workstation. Alternatively, thevehicle may drive through the workstation to another workstation. Forinstance, the workstation may include a plurality of locations referredto as pick locations. The vehicle may drive through the workstation tomove from a first pick station 205 to a second pick station.Alternatively, the vehicle may drive into the workstation, drive throughthe workstation and then exit the workstation to move to a differentworkstation where the vehicle will present an item for removal.

The system may optionally include a method for controlling the vehicleto present items, such as totes, at the workstation 200. For instance,the method may include the step of driving the vehicle 100 into theworkstation 200 and raising the vehicle upwardly. For instance, thevehicle may be raised upwardly toward an operator. Optionally, theworkstation may include an opening in an upper surface and the methodmay include the step of raising the vehicle so that a tote on thevehicle is positioned within the opening. Additionally, the opening maybe configured to correspond with the interior configuration of the tote.Further, the step of raising the vehicle may include the step of raisingthe tote until an upper edge of the tote is adjacent the underside ofthe upper surface and the interior of the tote is aligned with theopening. Further still, the step of aligning the tote may includepositioning the tote so that the interior of the tote substantiallyspans the opening to enclose the opening to impede items passing throughthe opening and outside the tote.

The method of controlling the vehicle to present items may optionallyinclude the step of tilting the totes as the totes are raised. Forinstance, the method may include the step of raising the vehiclesvertically upwardly and gradually displacing the vehicle relative to thehorizon so that a first edge of the vehicle is raised relative to asecond edge of the vehicle. Optionally, the step of raising the vehiclevertically upwardly may include the step of tilting the vehicle untilthe vehicle is tilted to a predetermined angle relative to the horizonand then raising the vehicle vertically upwardly at the predeterminedangle. Optionally, the system may selectively control the distance thatthe vehicle is raised vertically at a predetermined angle depending on acharacteristic of the item that the vehicle is carrying. Specifically,if the item is a first height, the vehicle may travel at a predeterminedangle for a first distance. If the item is a second height, the vehiclemay travel at a predetermined angle for a second distance that isgreater than the first distance.

The predetermined angle to which the vehicles are raised may correspondto the angle of the upper surface of the workstation so that the vehicleis tilted to an angle substantially parallel with the opening in theupper surface. Additionally, the system may be configured to accommodatetotes or containers of varying height at the workstation. For instance,the vehicle may be raised and tilted to the predetermined height andthen raised at the predetermined angle for a first distance for a totehaving a first height. Similarly, the vehicle may be raised at thepredetermined angle for a second distance for a tote having a secondheight. Preferably, in both instances the vehicles are raised so that anupper edge of the tote is adjacent the upper surface of the workstation.

Optionally, the steps of raising and tilting the vehicle 100 may includethe step of driving the vehicle up a track 250. The track may include apair of spaced apart curved forward track segments and a pair of spacedapart curved rear track segments. The method may include the step ofdriving the rearward edge of the vehicle at a higher speed to raise therearward edge of the vehicle relative to the forward edge of the vehicleto tilt the vehicle to a predetermined angle. After tilting the vehicleto the predetermined angle, the method may include the step of drivingthe rearward edge of the vehicle along the rearward track at a speedsubstantially similar to the forward edge of the vehicle along theforward track. Additionally, the step of driving the vehicle up thetrack may include the step of driving the front edge of the vehicle up afirst section of the front tracks having a first gear tooth pitch anddriving the vehicle up a second section of the front tracks having asecond gear tooth pitch.

Optionally, the step of driving the vehicle 100 up a track 250 mayinclude the step of rotating vertical drive gears 145 of the vehicleabout axes that are transverse the axes of rotation of a plurality ofdrive elements that drive the vehicle along a horizontal surface. Thestep of driving the vehicle up the track may optionally include the stepof driving the vertical drive gears in a first direction to drive atransfer gear 330 that meshes with the track 250. Driving the verticalgears in a first direction drives the transfer gear up the track. Thetransfer gear may have a first gear element having a first gear pitchand a second gear element having a second gear pitch. The method mayinclude the step of driving the vertical drive gears 145 to drive thefirst gear element up a first section of the track and continuing todrive the vertical drive gears 145 to drive the second gear element up asecond section of the track.

The system may optionally include a method for charging autonomousmaterial handling vehicles. The method may include the step of driving avehicle 100 into a workstation 200 to deliver an item. The vehicle mayinclude an electrical contact 160 and the workstation may include acharging element 340 for providing a charging current. The method mayinclude the step of electrically connecting the electrical contact 160of the vehicle with the charging element 340. For instance, the step ofconnecting may include the step of biasing the charging element towardthe charging contact and/or the step of biasing the charging contacttoward the charging element.

Additionally, the method of connecting may include the step of drivingthe vehicle toward the charging element to drive the electrical contact160 into electrical connection with the charging element 340.Optionally, the method includes the step of automatically adjusting theheight of the charging element 340 relative to the charging contact 160as the charging contact is displaced into electrical engagement with thecharging element. Additionally, the method may include the step ofautomatically adjusting the lateral positioning of the charging contactrelative to the charging element as the charging contact is displacedinto electrical engagement with the charging element.

The method of charging the vehicle may optionally include the step ofraising the vehicle vertically while continuing to charge the vehicle.For instance, the method may include the step of maintaining electricalengagement between an electrical contact 160 of the vehicle with acharging element 340 while the vehicle is displaced upwardly. Further, acharging current may be continuously provided to the charging element asthe vehicle is displaced upwardly at the workstation 200. Additionally,the charging current to the charging element may be maintained as thevehicle remains at a pick station 205 of the workstation 200 so that acharging current may be supplied to the vehicle while an operatortransfers items to or from the vehicle. The charging current may also besupplied to the vehicle while the vehicle is lowered downwardly. Themethod may optionally include the step of disengaging the vehicle fromthe charging element 340 by driving the vehicle away from the chargingelement.

The system optionally includes a method for delivering and retaining acontainer at a workstation 200. For instance, the method may include thestep of driving a vehicle carrying a container such as a tote to aworkstation and raising the vehicle to raise the container at theworkstation. While the tote is raised at a predetermined height at theworkstation, a retainer may retain the tote at the predetermined heightwhile the vehicle moves away from the workstation. For instance, thetote may be retained at the predetermined height while the vehicle islowered downwardly and then driven along a horizontal path away from theworkstation. While the tote is retained after the vehicle is displacedaway from the tote, the method may optionally include the step ofselectively accumulating a plurality of items into the tote.

Optionally, the items accumulated in the tote may be delivered by one ormore separate vehicles. For instance, the workstation 200 may include aplurality of adjacent pick stations 205 and each pick station may beconfigured to receive vehicles to deliver items to the workstation. Thetote 55 may be retained in a raised position by a retainer 290 at afirst pick station 205 of the workstation. While the tote is retained atthe first pick station, a vehicle may deliver an item to a second pickstation. The operator may remove an item from the vehicle at the secondpick station and place the item into the tote at the first station. Theprocess of vehicles delivering items to the second pick station toprovide items to be placed into the tote at the first pick station maycontinue until a predetermined set of items are placed into the tote atthe first pick station.

Once the predetermined set of items has been accumulated in the tote atthe first pick station, the tote may be removed from the first pickstation. Optionally, the tote may be removed by driving a vehicle intothe workstation and raising the vehicle upwardly toward the tote. Theretainer may then be disengaged from the tote to release the tote. Thevehicle may then be displaced downwardly along with the tote. Thevehicle may then be driven away from the workstation to drive the toteof accumulated items away from the workstation 200. It should beunderstood that the vehicle that retrieves the tote from the first pickstation may be different from the vehicle that delivers the tote to thefirst pick station.

Similarly, rather than accumulating items in the tote retained at thepick station, the method may include the step of removing items from theretained tote and feeding the items to a plurality of totes at one ormore separate pick stations. For instance, the tote retained at thefirst pick station may contain a plurality of items. At one or moreadjacent pick stations, a plurality of vehicles may deliver a pluralityof totes to the adjacent pick station(s). As each tote is delivered, theoperator may remove one or more of the items from the tote at the firstpick station and transfer the item(s) to the totes delivered to theadjacent pick station(s). In this way, the tote delivered to the firstpick station can provide a supply of items to be transferred to one ormore totes delivered to one or more adjacent pick stations. After itemsare transferred from the tote retained at the first pick station, themethod may include the step of raising a vehicle in the first pickstation and releasing the retainer to release the tote. The vehicle maythen be lowered downwardly along with the tote and the vehicle may bedriven away from the workstation along with the tote. It should beunderstood that the vehicle that retrieves the tote from the first pickstation may be different from the vehicle that delivers the tote to thefirst pick station.

Optionally, the system may also include a method for selectivelyenclosing an opening 216 in an upper surface 215 of the workstation 200.A covering such as a door 230 may be displaced over the opening 216 ofthe workstation 200 to impede items passing through the opening. Whilethe covering overlies the opening, a vehicle carrying a tote may beraised so the top edge of the tote is at a determined height adjacentthe upper surface 215. Once the tote is at the predetermined height, thecover may be removed from the opening to provide access to the totethrough the opening. In response to a signal that the transfer of itemsto or from the tote has been completed, a central controller 90 maycontrol operation of the doors to displace the covering over theopening. For instance, the controller may actuate a drive mechanism toclose the doors 230 over the opening 216. Additionally, the centralcontroller may control operation of the vehicle to retain the vehicle ina raised position to maintain the tote at the predetermined height untilthe doors are closed over the pick opening. After the doors are closed,the central controller may provide signals to the system to lower thevehicle along with the tote and then move the vehicle away. Forinstance, the central controller may provide signals to the vehicle todrive the vehicle downwardly to lower the vehicle.

The system may optionally provide a method for adjusting the verticaldrive 140 relative to the workstation 200 to provide clearance betweenthe vertical drive and the workstation as the vehicle drives into theworkstation. The vehicle may be driven into the workstation so that theteeth of vertical drive gears pass through the teeth of an element thatcooperates with the vertical drive gears to drive the vehicle upwardly.Driving the vertical drive gears in a first direction drives the vehicleupwardly in the workstation. Driving the vertical drive gears in asecond direction drives the vehicle downwardly.

To prevent the vertical drive gears from impacting the workstation whenthe vehicle is driven into the workstation, the position of one or moreteeth of each vertical drive gear may be monitored to ensure the teethare at a predetermined location relative to the workstation.Specifically, the method may include the step of monitoring thecircumferential location of a predetermined tooth of each vertical drivegear 145. The vehicle may enter the workstation and drive upwardly andthen downwardly. After the vehicle is driven downwardly to the ground,the position of the predetermined tooth of each vertical drive gear maybe measured relative to the workstation. For instance, the workstationmay include a gear that meshes with each vertical drive gear.Optionally, such gear may be the transfer gear 330. After the vehicle islowered to the ground, the position of the predetermined tooth of eachvertical drive gear may be detected to determine whether the tooth iswithin a predetermined circumferential range. The circumferential rangemay be determined relative to the tooth spacing of the gear that mesheswith the vertical drive gear to ensure that the vertical drive gears donot impact the meshed gear when the vehicle is driven parallel to theaxis of rotation of the meshed gear.

The system may also include a method for projecting information onto theworkstation 200 to aid the operator in handling items. For instance, acontainer such as tote 55 may be displaced into an opening 216 in theworkstation 200. A surface may be provided adjacent the opening 216. Forinstance, the surface may frame all or part of the opening. In theexample illustrated in FIG. 19 , the surface 215 optionally surroundsthe entire opening 216.

A projector 220 may be controlled to provide one or more projectionsonto the workstation to provide information to assist the operator. Forexample, the projector may provide a first light signal to provide asignal to the operator indicative of the item to be retrieved. Forinstance, the first light may illuminate items in the tote that are tobe retrieved. The tote 55 may include a plurality of dividers thatdivide the tote into a plurality of separate storage locations, referredto as cells 56. The projector may direct the first light 400 onto aparticular cell 56 so that the cell is illuminated while the remainingcells are not illuminated as shown in FIG. 19 . In this way, the firstlight signal may identify the location of the item to be retrieved.

The projector 220 may optionally provide a second light to provideinformation to the operator regarding the item to be retrieved. As shownin FIG. 19 , the second light signal 405 may be projected onto thesurface 215 of the workstation 200 adjacent the opening 216 in theworkstation. Optionally, the second light signal may be projected ontothe surface adjacent the location that the items are housed within thetote. For instance, as shown in FIG. 19 , the second light signal 405may be projected onto the surface 215 adjacent the first light signal400.

The second light signal may provide any of a variety of information toaid the operator to retrieve the item or items. For instance, as shownin FIG. 19 , the second light signal may identify the number of items tobe retrieved from the tote.

The method may also include the step of projecting a third light signalto provide further information to the operator regarding the item to beretrieved. Depending on the configuration of the surface 215 and theconfiguration of the second and third light signals, the third lightsignal 410 may be projected onto the surface 215 adjacent the firstlight signal and/or adjacent the second light signal 405. The thirdlight signal may be configured to provide information separate from theinformation provided by the second light signal 405. For instance, asshown in FIG. 19 , the third light signal may provide an icon orgraphical/pictorial representation of the item to be retrieved.

As described above, the projector may be configured to project aplurality of signals onto the items in the tote 55 or the work surface215 adjacent the tote. It should be understood that the projected visualsignals may vary in number and in configuration. For instance, FIG. 19illustrates an embodiment in which three different types of lightsignals are provided, a first that identifies the location of the item,a second that identifies the quantity of items to be retrieved and athird that identifies the item to be retrieved. However, in someapplications different information may be provided or only one or two ofthe light signals may be utilized. Similarly, additional light signalsmay be projected onto the tote 55 or the surface 215 of the workstation200 adjacent the tote.

In this way, the system may provide a method of processing items thatincludes the step of retrieving a container of item and transferring theitems to a workstation 200. The method may include the step ofprojecting a first light signal onto a portion of the container toidentify the location from which the item is to be retrieved from thecontainer. The method may include the step of simultaneously projectinga second light signal onto a surface 215 of the workstation thatidentifies the number of items to be retrieved from the identifiedlocation within the container. Optionally, the method may include thestep of projecting a third light signal onto a surface 215 of theworkstation 200 that identifies the item to be retrieved. The thirdlight signal may be provided instead of the second light signal or itmay be provided simultaneously with the second light signal.

The method may also include the step of actuating an actuator toindicate that the appropriate items have been retrieved from thecontainer. The actuator may be any of a variety of actuators, such as abutton or a touch screen display. In response to actuating the actuator,the container may be displaced away from the workstation. For instance,the container may be displaced away from the workstation by one of thevehicles 100.

It should therefore be understood that this invention is not limited tothe particular embodiments described herein but is intended to includeall changes and modifications that are within the scope and spirit ofthe invention as set forth in the claims.

What is claimed is:
 1. A workstation for material handling system havinga plurality of independently operable vehicles delivering items,comprising: a housing having a first opening configured to accommodatevehicles entering the workstation in a first horizontal orientation,wherein the opening is configured to permit the vehicles to pass throughthe opening while the vehicles carry containers; a track positionedwithin the housing so that vehicles driving through the opening in thehousing drive into operative engagement with the track, wherein thetrack is configured to guide vehicles vertically upwardly and whereinthe track comprises: a lower section having a curved profile configuredto tilt the vehicle to a tilted orientation that forms a predeterminedangle with the first horizontal orientation; an upper section having asubstantially linear profile configured to lift the vehicle verticallyat the tilted orientation.
 2. The workstation of claim 1 comprising amonitor for identifying the items to be removed from the containerdelivered by the vehicle to the pick station.
 3. The workstation ofclaim 1 wherein the lower section and the upper section each comprise aplurality of vertical tracks.
 4. A method for presenting items to anoperator at a workstation for a material handling system having aplurality of delivery vehicles operable to retrieve containers from arack of storage locations, wherein each delivery vehicle comprises avertical drive, wherein the method comprises the steps of: driving oneof the delivery vehicles to a workstation while the delivery vehiclecarries one of the containers; driving the vertical drive of thedelivery vehicle at the workstation in a first direction to lift thevehicle upwardly, wherein the step of driving the vertical drivecomprises: driving the vertical drive a first time to drive the vehicleupwardly and wherein the step of driving the vertical drive a first timecomprises tilting the container at an angle relative to the horizon;driving the vertical drive a second time to drive the vehicle upwardlywhile maintaining the container at the angle relative to the horizon. 5.The method of claim 4 comprising the step of driving the vertical driveof the delivery vehicle in a second direction to lower the deliveryvehicle.
 6. The method of claim 5 comprising the step of driving thedelivery vehicle away from the workstation after the step of driving thevertical drive in a second direction.
 7. The method of claim 4 whereinthe workstation comprises a track having a plurality of first driveteeth and a plurality of second drive teeth configured differently thanthe first drive teeth, wherein the step of driving the vertical drive afirst time drives the vehicle along the first drive teeth and whereinthe step of driving the vertical drive a second time drives the vehiclealong the second drive teeth.
 8. The workstation of claim 1 wherein thetrack comprises a plurality of teeth and the lower section of the trackcomprises a first track element having a first tooth pitch and a secondtrack element having a second tooth pitch.
 9. The workstation of claim 8wherein the first track element opposes the second track element so thata first wheel of the vehicle is engageable with the first track as asecond wheel of the vehicle in engageable with the second track.
 10. Theworkstation of claim 8 wherein the upper section comprises a first trackelement connected with the first track element of the lower section anda second track element connected with the second track element of thelower section.
 11. The workstation of claim 10 wherein the first andsecond track elements of the upper section have the first tooth pitch.12. The workstation of claim 11 wherein the plurality of independentlyoperable delivery vehicles comprise vertical drive elements and theworkstation comprises a transfer gear cooperable with the vertical driveelements and the track.
 13. The workstation of claim 12 wherein thetransfer gear comprises a first section having a first tooth pitch forcooperating with the first tooth pitch of the second track element ofthe upper track and a second tooth pitch for cooperating with the secondtooth pitch of the second track element of the lower section.
 14. Themethod of claim 4 wherein the step of driving the vertical drive asecond time comprises selectively driving the vertical drive in responseto the height of the container on the vehicle.
 15. The method of claim14 wherein the distance that the vertical drive is driven during thestep of driving the vertical drive a second time is inverselyproportional to the height of the container on the vehicle.
 16. Themethod of claim 14 wherein the step of selectively driving the verticaldrive in response to the height of the container on the vehiclecomprises selectively driving the vertical drive a first distance for acontainer having a first height and selectively driving the verticaldrive a second distance for a container having a second height that isdifferent from the first height.
 17. A material handling systemcomprising: a plurality of independently operable vehicles fordelivering items, comprising: a rechargeable power supply and a verticaldrive; a workstation, comprising: a housing having a first openingconfigured to accommodate vehicles entering the workstation in a firsthorizontal orientation, wherein the opening is configured to permit thevehicles to pass through the opening while the vehicles carrycontainers; a track positioned within the housing so that vehiclesdriving through the opening in the housing drive into operativeengagement with the track, wherein the track is configured to guidevehicles vertically upwardly and wherein the track comprises: a lowersection having a curved profile configured to tilt the vehicle to atilted orientation that forms a predetermined angle with the firsthorizontal orientation; an upper section having a substantially linearprofile configured to lift the vehicle vertically at the tiltedorientation.
 18. The material handling system of claim 17 comprising acontroller configured to provide signals for controlling movement of thevehicles to selectively drive the vertical drive of one of the vehiclesin response to the height of the container on the one vehicle.
 19. Thematerial handling system of claim 17 wherein each vehicle comprises apair of spaced apart vertical drive elements and wherein the lowersection of the track comprises a first curved track having a first toothpitch and a second curved track spaced apart from the first curved trackhaving a second tooth pitch.
 20. The material handling system of claim19 wherein the upper section of the track comprises a first straighttrack projecting from an end of the first curved track transverse thehorizon and a second straight track projecting from an end of the secondcurved track parallel with the first straight track portion.